I have a lot of storage heaters but would like to come off of E7 and switch to a time of use tariff, (E7 is now very expensive 12p night & 21p day.) I'm thinking of using a mechanical Immersion heater timer rated at 16 amp in the place of the on/off switch box next to each heater. I think this will be okay for the heaters (each charge at 3.4kw) Does this sound reasonable? I am acutely aware that there could be factors I am ignorant of. I know exactly nothing about electrics so would be getting a sparks to do the work (inc removing the main E7 timer in the meter box) by the way I asked 'Timeguard' the maker of the immersion heater timers (NTT01) and they just said they will not comment of the use of their devices ! !